Osteoporotic fracture prevention has historically focused on bone mineral density as measured by DEXA scanning. This is an important but incomplete picture. Studies examining fractures in population cohorts consistently find that more than 50 percent of hip fractures occur in women with T-scores in the osteopenic range, not in the osteoporotic range. This is not because osteopenia is equally dangerous to osteoporosis; it is because far more people have osteopenia than osteoporosis, and bone density is only one component of fracture risk.
The FRAX Tool and Its Limitations
The FRAX tool, developed by the World Health Organisation, calculates a 10-year fracture probability using bone density, age, weight, height, smoking status, alcohol consumption, parental hip fracture history, glucocorticoid use, secondary osteoporosis, and rheumatoid arthritis. It is widely used in UK clinical practice to guide treatment decisions. What it does not capture is muscle strength, physical function, gait speed, reaction time, and indoor fall hazard assessment, all of which are independently predictive of fracture.
Fall Risk Is as Important as Bone Strength
- Lower limb muscle weakness: hip and knee extensor weakness is the strongest single predictor of fall risk; directly addressable through resistance training
- Gait speed: walking speed below 0.8 metres per second is associated with significantly elevated fall and fracture risk
- Balance: single-leg standing time below 10 seconds at age 65 is a clinically meaningful fall risk marker
- Polypharmacy: multiple medications, particularly sedatives, antihypertensives, and antidepressants, increase fall risk by impairing balance and reaction time
- Visual impairment: uncorrected visual decline is a significant and correctable fall risk factor
- Indoor hazards: loose rugs, poor lighting, and absence of grab rails are modifiable contributors to hip fracture incidence
Sources
- Kanis, J.A., et al. (2008). FRAX and the assessment of fracture probability in men and women from the UK. Osteoporosis International, 19(4), 385-397.
- Tinetti, M.E., et al. (1988). Risk factors for falls among elderly persons living in the community. New England Journal of Medicine, 319(26), 1701-1707.
- Studenski, S., et al. (2011). Gait speed and survival in older adults. JAMA, 305(1), 50-58.